I moved my profile, all game saves and all my XBL Arcade titles to a USB key yesterday without issue. All that remains on the HDD now is installed games or DLC. My 8GB stick is not even half full - I may pick up a super fast 16GB one and get a game or two on it. GoD games become a little more attractive to me as it'd be cool to have multiple executable games on something I can fit in my pocket. There is no noticeable speed difference that I can ascertain - theoretically I'd expect random reads to be quicker (no spindle to spin up) and sustained data transfer to be comparable or maybe a touch slower (HDDs still do this better than NAND, but the 360 drives are not the quickest).